Nuclear power stations have been an important energy source for our society for many years. With so many different kinds of nuclear reactors being around the world, the pollution of the radioactive wastes and also the possibility of disastrous accidents have been an important issue. The Chernobyl reactor accident of 1986 resulted in exposure to high radiation doses for some people, well above the lethal level. It also gave millions of people all across Europe increased radiation as compared to the natural background levels. Thousands would eventually die prematurely. In 1993 more than 10 percent of Ukraine's national budget was used for cleaning up after the accident.1
1 Washington Post, Oct. 22, 1993. 
With the end of the Cold War, eliminating the environmental problems created by the nuclear weapons becomes an emerging issue. A 1991 report by Congress's Office of Technology Assessment found evidence that “air, groundwater, surface water, sediments, and soil, as well as vegetation and wildlife, have been contaminated at most, if not all, of the Department of Energy nuclear weapons sites.”2
2 Washington Post, Oct. 22, 1993. 
With such large amount of contaminated waste, conventional solidification or separation methods are not always practical. They are either too expensive, too bulky, too time-consuming, or cause other chemical contamination.
Numerous efforts have been undertaken regarding solid nuclear waste treatment. Several processes have been developed for separation and solidification of the radioactive waste. One process is an encapsulation method developed by Brookhaven National laboratory. Low density polyethylene is heated above their melting point and mixed with the radioactive waste. The whole system is then cooled down and the waste is therefore solidified. The polyethylene provides greater long-term stability than concrete and asphalt, which were popular materials for solidification, since polyethylene is an inert, low permeability plastic that is highly resistant to chemical attack, biodegradation, and radiation damage. However, this process does not provide for separation of radioactive and non-radioactive wastes. Thus, the volume of the waste is not reduced. It is also difficult to perform the process in an emergency situation.
Another process has been developed by Westinghouse Electric Corp. to separate the particles by using radiation detecting devices and mechanical separating devices.3 Waste particles are scanned individually and then separated to different collectors based on their radiation. The process involves large and complex machinery and is not practical for small particle separation.
Washington Post, Oct. 22, 1993. 
It is clear that there is a need in the art for a process that can separate radioactive particles from solid waste highly selectively, completely, rapidly, and inexpensively.